Apparatus for automatically copying lines

ABSTRACT

LINES ARE DRAWN BY A BEAM OF LIGHT PROJECTED FROM A MOVABLE HOUSING ONTO A PHOTOSENSITIVE MATERIAL. A DOVE PRISM ROTATES THE BEAM ACCORDING TO ITS DIRECTION OF MOVEMENT, AND MEANS ARE PROVIDED TO VARY THE INTENSIVTY OF THE BEAM IN RESPONSE TO VARIATIONS IN ITS VELOCITY WITH RESPECT TO THE PHOTOSENSTIVE MATERIAL, THEREBY PROVIDING CORRECT EXPOSURE ALONG THE LENGTH OF A LINE. THE HOUSING ALSO CARRIES APPARATUS FOR PROJECTING SYMBOLS ONTO THE PHOTOSENSITIVE SURFACE.   D R A W I N G

Jan. 11, 1972 o. C. RITCHIE Er APPARATUS FOR AUTOMATICALLY COPYING LINESOriginal Filed June 5, 1964 5 Sheet-Sheet 1 Inventors A Horne y Jan. 11,1972 v D. C. RITCHIE ETAL Re. 27,265

APPARATUS FOR AUTOMATICALLY COPYING LINES 3 Sheet-Sheet 2 Original FiledJune :5, 1964 I n v e n [07:

DAV/ S042 n/ 19/ rc/ms M Attorney Jan. 11, 1972 0. c. RITCHIE ErAL Re.27,265

APPARATUS FOR AUTOMATICALLY COPYING LINES Original Filed June 5, 1964 3Sheet-Sheet S MW aw Attorney United States Patent 27,265 APPARATUS FORAIiTIg% ISATICALLY COPYING David Scarth Ritchie, Glasgow, and ThomasMcPherson Glass, Edinburgh, Scotland, assignors to Barr and Stroud Ltd.,and D-Mac Limited, both of Glasgow, Scotland, Great Britain, fractionalpart interest to each Original No. 3,323,414, dated June 6, 1967, Ser.No. 373,607, June 3, 1964. Application for reissue Aug. 13, 1968, Ser.No. 785,817

Int. Cl. B41b 13/00; 43m 13/18 U.S. Cl. 95-12 30 Claims Matter enclosedin heavy brackets appears in the original patent but forms no part ofthis reissue specification; matter printed in italics indicates theadditions made by reissue.

ABSTRACT OF THE DISCLOSURE Lines are drawn by a beam of light projectedfrom a movable housing onto a photosensitive material. A dove prismrotates the beam according to its direction of movement, and means areprovided to vary the intensity of the beam in response to variations inits velocity with respect to the photosensitive material, therebyproviding correct exposure along the length of a line. The housing alsocarries apparatus for projecting symbols onto the photosensitivesurface.

This invention relates to apparatus for automatically drawing lines,particularly but not exclusively irregular lines, for example forcartographic purposes. The apparatus may also be used for printingsymbols.

Hitherto, finished maps and charts are hand-drawn from originalmanuscript maps by highly skilled draughtsmen, but the finishing processis lengthy and laborious, particularly when changes between the originalmanuscrip and finished map are involved. Said changes may be forexample, scale or projection, the insertion of dotted and parallel linesand changes in thickness and tone of line.

It is an object of the invention to obviate or mitigate theabove-mentioned disadvantages.

According to the present invention we provide apparatus forautomatically drawing a line, for example as on a map, in accordancewith recorded data, which data may be, for example, in the form ofelectrically magnetized tape giving the position of each part on theline relative to co-ordinate axes, comprising means for projecting alight beam to effect a trace of the line, for example onphotographically sensitised paper, and means for automatically movingthe light beam relative to co-ordinate axes with components of movementcorresponding, for example, to the distance of the parts of the linefrom the co-ordinate axes.

The apparatus may also include a facility for projecting a symbol atspecific points, or a series of symbols or marks at specified points, ora series of symbols or marks at specified intervals along the trace of aline.

Preferably the means for moving the light beam includes relativelymovable carriages mounted for movement mutually at right angles andelectrically driven with components of movement in accordance withelectrically recorded co-ordinated data. Alternatively means for movingthe light spot in polar co-ordinates can be provided.

Further according to the invention the apparatus may include means tomask a portion of the light in order to provide a plurality of paralleltrace lines, comprising a light transmitting element having an opaquezone of varying width thereon, said element being movable in order tobring any selected part of the opaque zone into "ice position to maskpart of the light beam and thus form spaced images of the original line.

The apparatus preferably includes a dove prism, situated in parallellight, which inverts light passed therethrough but does not change thedirection of same, said prism being automatically maintained in aspecific relationship with the direction of tracing by the light beam,in order to maintain the trace lines parallel. Also, there may beprovided means for intermittently interrupting the trace, for example,comprising a light deflector adapted to be intermittently moved in orderto deflect the light beam out of and into the tracing position.

In order to adjust the width of trace line an adjustable diaphragmpreferably square in shape is positioned in the beam of light. In orderto produce a variety of symbols a disc is provided carrying a number ofsymbols, any one of which may be introduced at a time into the projectedbeam. A separate means is provided to control the exposure of thesymbols independenty from that of the lines.

The apparatus preferably includes control circuits to control theintensiyt of the light according to the speed of movement, control theinterruption of the light beam if broken lines are required, and toensure that the spaced beams of light are maintained at right angles tothe direction of motion of the head.

An embodiment of the invention will now be described, by way of example,with reference to the accompanying drawings, in which:

FIG. 1 is an axial sectional elevation of a projector;

FIG. 2 is a diagrammatic sectional end view on the line I*I-II of FIG.1, and

FIG. 3 is a block diagram of the control circuit.

Referring now to FIG. 1, reference 21 denotes a light source located inthe projector, the rays emanating from which source are condensed by alens system 20. A square diaphragm 4 (seen best in FIG. 2) is positionedco-axial with the lens system 20, and the size of the diaphragm iscontrolled by a servo-motor 3A housed in a casing 13.

Adjacent the diaphragm 4 is a transparent disc 5 pivotally mounted on anaxis parallel to the beam of light emanating from the source 21. Markedon the surface of the transparent disc is an opaque arcuate zone 14 ofvarying width FIG. 2), the disc 5 being so positioned that any part ofthe opaque arcuate zone may be coincident with the axis of said lightbeam in order partially to mask same. Rotation of this disc is manuallycontrolled.

The beam of light is deflected through a right angle by means of adeflector 7, e.g. a plane mirror which is carried on a moving element ofan electrical interruption relay 6 which relay when energised causes asmall angular rotation of the moving element. This relay 6 is energisedby an electric pulse generator as will be described hereinafter. Thebeam of light is passed from the mirror 7 via a fixed prism [7a] to aprojecting lens system comprising two lenses 8. Interposed between thelenses 8 is a dove prism 9 which inverts, but does not change thedirection of, the light passed therethrough. The dove prism 9 is used torotate the image of the light and is mounted for rotational movementabout the axis of the reflected beam, such rotational movement beingcontrolled by a servo-motor [3A]. The emergent ray from the projector isdirected normally on to a photographically sensitised sheet 12.

'If a symbol 29 is required to be printed then an in-.

terruption relay or solenoid 23 carrying a reflector 22 is operated. Asmall rotation of the reflector 22 allows an image of the requiredsymbol 29 on a disc 24 to be projected through a branch optical system,consisting of condenser 25 and projector 26, into the main opticalsystem via a beam combining prism 27. The disc carrying the symbols ismounted on the same rotating holder vs that which mounts the disc 5carrying the opaque .rcuate zone 14. Individual symbols can be manuallyelected and the disc registered in position by means of spring loadedpawl 28. Means are provided for re noving individual symbols 29 from thedisc and relacing them with different symbols. The same light ource isused to illuminate the symbols as is used to lluminate the squarediaphragm.

The projector may be mounted for translational movement in twodirections on a gantry comprising two roller :arriages 10, 11 mountedmutually at right angles, roller arriage being superimposed on rollercarriage 11 and leing free to move in a direction at right angles to thelirection of motion of carriage 11.

The resultant motion of the projector consists of two mutuallyperpendicular components of motion, which are iarallel to tworectangular co-ordinate axes, and is ffected by electronic controlsystem, the control system eing supplied with information, for exampleas stored in a magnetic tape or punched cards. The mutuallyrerpendicular components of motion of the projector are lependent uponthe co-ordinates of each part of the riginal line with respect to theaforesaid rectangular 'eference axes. Thus, the projector travels over apath n accordance with the recorded data. Control systems f this typeare already known in this art, as in Patent Jo. 3,258,776.

In operation, light from the light source 21 is contensed by thecondensing lens system and is conentrated at the diaphragm 4, theaperture of which is 'ariable within limits in order to vary thethickness If line. The light then passes through a transparent ector ofthe disc 5, but if a divided ray of light is reuired in order to producea double line, the disc is otated the required amount by hand.

The light is then deflected through a right angle, by means of the planemirror 7 to the projecting lens system i from which the emergent ray isprojected normally n1 to the photographically sensitised sheet 12, theproecting lens system 8 being such that the dove prism s situated inparallel light. Thus as the projector moves [1 a predetermined path thespot or spots of light on the thotographically sensitised sheet 12 traceout the same vath leaving a photographic record of the said path.

If a dotted line is required to be formed then the lectricalinterruption relay 6 is energized at short inervals, upon whichenergisation the moving element of he relay 6 is given a small angularrotation which is [1 turn imparted to the plane mirror 7. This causesthe efiected light to be displaced and hence during the reriod when therelay is energised no light is projected '11 to the photographicallysensitised sheet 12.

If it is required to expose a symbol 29 at specified lOlIltS, theappropriate symbol is selected and the relay ,3 in the branch opticalsystem is energised.

If the symbol or mark is required at specified intervals long the traceof a line this can be produced by energisng the relay at appropriateintervals to produce the exosure. In the latter case the marks aresuperimposed ill the trace of the line and are maintained in the sameotational relationship to the direction of the trace by he dove prism 9.

The control of the intensity of the light source 21, learn interrupters[14] 6 and 23, and dove prism 9 is obained from the rotation oftacho-generators attached 0 servo-motors which drive the gantry in the Xand Y lirections as illustrated in FIG. 3. The outputs from vlternatingcurrent tacho-generators 31 vary in amplitude vs the motor speed variesand these signals are fed via solating amplifiers 32 to the rotor coilsof a resolver ynchro 3-3. One of the stator coils supplies an amplifierl4 and servo-motor 3C which drives the rotor to the lull point. At thispoint the output R of the other stator :oil equals /K(Vx -Vy where K isa constant and 4 Vx and Vy are the input voltages into the resolver 33from X and Y tacho-generators 3 respectively.

The resolver has thus changed the voltages representing the speeds ofthe X and Y movements from cartesian co-ordinate values into polarco-ordinate values R and 0. [R0]. The dove prism 9' is rotated by theshaft of the servo-motor 3C and thus aligns the spaced beams at rightangles to the direction of motion of the head when drawing double lines.When drawing single lines the square image of the diaphragm ismaintained with a side at right angles to the direction of tracing theline. The voltage output R is rectified in a rectifier 36 to give a DC.voltage and the DC. voltage is used to control the light sourceintensity unit 37 in such a way that the photographic recording materialreceives the correct exposure over the full range of speeds, A feedbacksystem using a photoelectric cell is employed to ensure that the lampintensity called for by the control unit has been achieved. The D.C.voltage from the rectifier 36 is also supplied to a variable rate pulsegenerator 38. The output pulses from this generator are divided andcounted by a pattern generator 39 whose output controls the interruptionof the light beam by interruption relays 6. Adjustment is provided sothat the counting pattern can be altered to give a variable mark/spaceratio on the interrupted line being drawn, but the circuit is such thatthe marked lines remain appreciably constant in length independent ofspeed and direction of motion. The same system is used for controllingthe exposure of symbols or marks at specified intervals to besuperimposed along the length of a line trace; in the latter case therelay 23 in the secondary optical system is controlled by the outputpulses from the generator.

Referring to FIG. 2, the diaphragm 4' has an aperture 40, the centre ofwhich is coincident with the axis of the light beam, the size of theaperture 40 being controlled by the servo-motor 3A in conjunction with apotentiometer 15 or by hand. The electrical control may also be fromrecorded information or remotely by hand. The transparent disc 5 ispivotally mounted on an axis indicated at 41 which is also the centre ofthe mean curvature of the opaque arcuate zone 14, rotation of said disc5 being manually controlled, but remote manual or automatic control canbe added.

It is desirable that only essential equipment he included in theprojector so as to keep its weight to a minimum and thus reduce itsinertia when in motion.

In a modification of the invention the projector is moved in polarrather than cartesian co-ordinates.

As a result of the invention a system has been devised which is intendedsubstantially to automate the work of drawing lines and is particularlyuseful for producing finished maps and charts, some advantages of thesystem being that, singles lines, accurately parallel spaced and dottedlines can be produced, in addition to scale and projection changes,automatically.

We claim:

1. Apparatus for producing a line trace by movement of a light beamalong a predetermined path, comprising means for projecting a light beamalong at least one optical axis, means for moving the light beamtransverse to said axis through points whose coordinates have no regulararithmetic relationship to each other, thereby to move said axis along abent line, and means responsive to said moving means for rotating saidlight beam about said axis so that said light beam maintains a fixedorientation relative to the direction of said line trace at theintersection of said axis and said line trace.

2. Apparatus as claimed in claim 1, said rotating means comprising prismmeans, and means for bodily rotating said prism means about said axis.

3. Apparatus as claimed in claim 2, said prism means comprising a doveprism.

4. Apparatus as claimed in claim 1, said projecting means comprising arectangular diaphragm, said rotating means maintaining a side of theopening bordered by said diaphragm perpendicular to said direction.

5. Apparatus as claimed in claim 1, and means for disposing an opaquearea within said light beam whereby said light beam projects a formedimage.

6. Apparatus as claimed in claim '5, said means for disposing an opaquearea comprising a transparency having thereon an opaque line of varyingwidth, and means for moving said line perpendicular to said axis therebyto produce an image having two illuminated portions spaced by a darkenedportion of predeterminable Width.

7. Apparatus as claimed in claim 6', and means mounting saidtransparency for rotation about an axis parallel to but spaced from saidoptical axis, said opaque line being arcuate about said axis of rotationof said transparency.

-8. Apparatus as claimed in claim 5, said disposing means comprisingmeans for selectively positioning any one of a series of ditferentsymbols along said optical axis.

9. Apparatus as claimed in claim 8, said disposing means comprising adisc, and means mounting said disc for rotation about an axis parallelto said optical axis, said symbols being spaced arcuately about saiddisc.

10. Apparatus as claimed in claim 1, said projecting means comprisingmeans for intermittently interrupting said light beam.

11. Apparatus as claimed in claim 10, said interrupting means comprisingan optical element for transmitting said light beam, and means formoving said optical element to deflect the light beam.

12. Apparatus as claimed in claim 1, and means for superposing a secondimage on said light beam.

13. Apparatus as claimed in claim 12, said superposing means including acombining prism, one of said light beam and said second image passingthrough said combining prism and the other of said light beam and saidsecond image being deflected by said combining prism along said opticalaxis so that said light beam and said second image leave said combiningprism optically coaxial.

14. Apparatus for producing a line trace by a light beam comprisingmeans for projecting a light beam along an axis onto a sheet ofphotographic recording material, means for moving said light projectingmeans at varying speeds along a bent line over the photographicrecording material to efiect a trace of a line thereon, means forgenerating a signal which varies according to the speed of the lightbeam relative to the material and means responsive to said signal forcontrolling the intensity of the light beam according to the speed ofthe light projecting means to provide correct exposure of thephotographic recording material throughout the movement of the lightprojecting means at the varying speeds.

15. Apparatus according to claim 14 wherein the projecting meansincludes an opaque member with a transparent area which provides alight-transmitting zone in the path of light passing to the photographicrecording material, and means for changing the size of thelighttransmitting zone aligned with the beam in order to change the sizeof the beam striking the photographic recording material.

16. Apparatus according to claim 15 having a condenser lens in the pathof light leading to the opaque member.

17. Apparatus according to claim 14 having a first carriage supportingthe projecting means for movement in one linear direction parallel tothe photographic recording material, and a second carriage supportingthe first 6 carriage and the projecting means for movement in anotherlinear direction which is perpendicular to the one linear direction andparallel to the photographic recording material.

18. Apparatus according to claim 17 wherein the projecting means alsoincludes an opaque carried having a plurality of difierent transparentsymbols thereon, means supporting said carrier for movement to selectany one of said symbols, and means for directing light through theselected one of said symlbols and onto the photographic recordingmaterial.

19. Apparatus according to claim 17 having means for varying the crosssectional area of the light beam.

20. Apparatus for drawing with light on a photographic recordingmaterial comprising, means for producing a line trace by moving a lightbeam in a path over photographic recording material; symbol projectingmeans comprising an opaque carrier having a plurality of differenttransparent symbols, means supporting said carrier for movement toselect any one of said symbols, and means for projecting a light beamthrough a selected one of the symbols and onto the photographicrecording material to create an image of the selected one of saidsymbols on the photographic recording material, said apparatus having afirst carriage supporting the symbol projecting means for movement inone linear direction parallel to the photographic recording material,and a second carriage supporting the first carriage and the symbolprojecting apparatus for movement in another linear direction which isperpendicular to the one linear direction and parallel to thephotographic recording material.

21. Apparatus according to claim 20 wherein the carrier is supported forrotational movement, and the symbols are circumferentially spaced aparton the carrier.

22. Apparatus according to claim 21 having on optical condenser in thepath of light leading to the carrier.

23. Apparatus according to claim 20 wherein the means for producing aline trace includes means for controlling the intensity of the lightbeam according to the speed of the optical head to provide correctexposure of the photographic recording material.

24. Apparatus according to claim 20 wherein the moving light beam whichforms a line trace and the light beam which creates an image of theselected one of the symbols are projected on the photographic recordingmaterial by a common projection lens means.

25. Apparatus according to claim I having means for controlling theintensity of the light beam according to the speed of the light beamalong said predetermined path to provide correct exposure of thephotographic recording material.

26. Apparatus for producing a line trace by a light beam, comprisingmeans for holding a sensitized sheet,

means for projecting a light beam along an axis onto a sheet ofsensitized photographic recording material held on said holding means,

means for effecting relative movemem between said light projecting meansand said holding means at varying speeds to efiect a predetermined linetrace on the photographic recording material, said relative movementbeing the resultant of movements respectively confined to first andsecond mutually-perpendicular linear directions which lie parallel tothe recording material,

means for deriving first and second signals respectively indicative ofthe speed of said movements along said first and second directions,

signal-combination means for changing said signals into a singlecombined signal which represents the vector sum of the first and secondsignals, and

means for varying the intensity of the light beam in response to thecombined signal to provide correct exposure of the photographicrecording material.

27. Apparatus according to claim 26 wherein first and econd carriagesare provided to confine said movements espectively to said first andsecond linear directions, said peed derivation means provides signalsindicative of the peeds of each of said first and second carriages, andsaid ignal-combination means in a resolver.

28. Apparatus according to claim 27 wherein the first arriage supportsthe projecting means and the second arr-iage supports the firstcarriage.

29. Apparatus according to claim 26 wherein the prozcting means alsoincludes an opaque carrier having a 'lurality of diflerent transparentsymbols thereon, means upporting said carrier for movement to select anyone of aid symbols, and means for directing light through the electedone of said symbols and onto the photographic ecording material.

30. Apparatus according to claim 26 including means esponsive to themeans for efiecting relative movement 9 rotate said light beam aboutsaid axis so that said light eam maintains a fixed orientation relativeto the direcion of said line trace at the intersection of said axis andaid line trace.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,149,490 8/1915 Bagge 4.5 3,004,469 10/1961Broyer 8824 3,103,849 9/1963 Wise 8824 3,247,761 4/1966 Herreman 95123,041,932 7/1962 Kilrninster 35520 3,116,661 1/1964 Holland 954.53,169,458 2/1965 Wilson 954.5 3,458,253 7/1969 Hansen 35519 FOREIGNPATENTS 834,025 5/ 1960 Great Britain 35520 JOHN M. HORAN, PrimaryExaminer US. Cl. X.R. 9512

